Spatial-temporal dynamics of HZ prevalence among high-risk groups: a global multiregional cohort analysis since 1990

BACKGROUND: Herpes zoster (HZ) is caused by the reactivation of the varicella-zoster virus (VZV). Individuals aged 50 years and older are at high risk due to immune aging. The Global Burden of Disease Study (GBD 2021) provides multidimensional data across regions and time series for analyzing HZ epidemiological characteristics in high-risk groups. However, studies on inequalities stratified by the Socio-demographic Index (SDI) and future trend predictions for these groups are still lacking. METHODS: Based on the GBD 2021 database, we extracted data on HZ incidence and disability-adjusted life years (DALYs) among individuals aged ≥ 50 years in 204 countries and regions from 1990 to 2021. We used the Age-Period-Cohort (APC) model, inequality indices (SII/CI), frontier analysis, and BPAC prediction models, combined with stratification by the Socio-demographic Index (SDI) and geography, to explore the spatiotemporal dynamics and driving factors of the disease burden and predict trends up to 2035. RESULTS: From 1990 to 2021, the global incidence of HZ in high-risk groups increased from 5.48 million to 12.49 million cases (a 128% increase), with the age-standardized incidence rate (ASIR) rising slightly from 640.9 to 654.1 per 100,000 (EAPC 0.1%). DALYs increased from 141,000 to 220,000 (a 56.8% increase), while the age-standardized DALY rate (ASDR) decreased from 18.27 to 11.90 per 100,000 (EAPC - 1.45%). SDI stratification revealed a pattern of "higher incidence but lower burden in high SDI regions, and lower incidence but higher burden in low SDI regions." Women and individuals aged ≥ 90 years had the highest burden. APC analysis showed that age was the core driving factor, with the period effect indicating a peak in incidence around 2005 and a continuous decline in DALYs due to medical interventions. The cohort effect showed a lower disease burden in younger cohorts. The number of cases is predicted to continue rising by 2035, while the ASIR will fluctuate at a high level. CONCLUSION: The disease burden of HZ in high-risk groups is driven by multiple factors, including aging, gender, SDI, and access to medical care, showing significant multidimensional disparities. Stratified precision prevention and control measures (strengthening surveillance and elderly interventions in high SDI regions, and supplementing basic medical resources in low-middle SDI regions), widespread vaccination, and international resource redistribution are needed to curb the rising disease burden and promote global health equity.